The present invention relates to a rotating electrical machine control device.
In a three-phase modulation mode of a three-phase inverter in which a three-phase alternating current is generated and applied to respective phases coils of a three-phase alternating current rotating electrical machine by three-phase PWM switching, there is a high switching loss in electric power since the PWM switching is performed with respect to three phases, and the switching to a two-phase modulation mode from the three-phase modulation mode is performed in an operation region where a current distortion by a two-phase modulation is small (for example, see Japanese Patent No. 3844060). Note that the two-phase modulation mode is executed by stopping the PWM switching for forming a sine wave in one phase to obtain a continuous high level or low level in a half wave interval and sequentially switching the phases.
In a rotating electrical machine control using a vector control, it is necessary to detect a rotation angle (magnetic pole position) q of an electric motor in order to perform a feedback of the operation state of the electric motor to the vector control. Japanese Patent Application Publication No. JP-A-2007-151344 describes a sensor less motor control that estimates and calculates the magnetic pole position based on a motor current, extracts a high frequency component of the motor current to calculate a magnetic pole position correction amount based thereon, and corrects the magnetic pole position. There are also embodiments in which the magnetic pole position is detected by connecting a rotary encoder or a resolver to an electric motor.
In the resolver, a rotor having a winding that is excited by a high frequency current is driven to rotate by the electric motor, and a voltage induced in a stator winding and having an excited current frequency is increased/decreased (modulated) by the rotation of the rotor. This is passed through a high-pass filter (demodulated) to output a sine wave (or a cosine wave) showing the rotation of the rotor as a rotation detection signal showing the rotation angle and the rotational speed of the electric motor. The phase of the rotation detection signal corresponds to the rotation angle (electric angle θ) of the electric motor, and the frequency is proportional to a rotational speed w of the electric motor. From the rotation detection signal, the rotation angle θ and the rotational speed ω of the electric motor can be calculated by an angle/speed calculation.
Note that Japanese Patent Application Publication No. JP-A-10-66383 describes a motor drive control device including a boost circuit that omits a weak field control in order to eliminate electric loss or a decrease in system efficiency due to the weak field control and increases the operation voltage applied to an inverter, in which electricity is supplied from the boost circuit to the inverter when a battery voltage is insufficient with respect to a target operation of the motor. Japanese Patent No. 3746334 describes a motor drive control device including a boost circuit, which increases a battery voltage, in which the boost circuit is controlled such that a required boost voltage corresponding to a target operation and speed electromotive force of a motor is calculated to realize the boost voltage.